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Removing load-bearing walls
Opening up rooms or creating open-plan layouts where a wall is carrying floor or roof loads above.
Homeowner guide
When you need a structural engineer.
If you are removing walls, adding an extension, converting a loft or changing how your home carries weight, a structural engineer is usually involved. This guide explains why and when.
What they do
The technical role behind the safe build.
A structural engineer designs and checks the load-bearing parts of a building: beams, foundations, floors and roofs. They produce the calculations and drawings that Building Control will expect to see for many residential projects.
On site, the engineer's drawings give the builder precise instructions for how the structural work should be done. That removes guesswork and reduces avoidable rework.
When a structural engineer is usually needed.
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Extensions
Single-storey, two-storey, side-return and rear extensions, where new structure ties into the existing home.
roofing
Loft conversions
Loft conversions where the roof structure, floor joists and any new openings need designing properly.
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Steel beams and openings
Installing RSJs, lintels or large openings such as bi-fold doors that change how loads are carried.
foundation
Foundations and basements
Underpinning, basement excavations and significant foundation changes that affect the stability of the property.
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Anything Building Control flags
Any project where your local Building Control team asks for structural calculations as part of the approval.
Typical UK costs
Useful budget ranges to plan around.
As a rough guide for residential work, a single beam calculation is often £250–£400, a loft conversion structural package £400–£800, and a full extension design around £800–£1,500. Larger or more complex projects, such as basements or multi-storey alterations, typically start from £2,000.
Costs vary by project, region and engineer, so always confirm the fee in writing before instructing. This guidance is general information rather than engineering or legal advice.
How we can help
Pointing you to the right person at the right time.
If your project needs structural input, we can suggest when to bring an engineer in and, where useful, point you towards engineers we have worked alongside on residential projects.
Ready to find a suitable builder?
Tell us about your project and we will introduce you to suitable local builders and help you compare their quotes.